RAINFALL FREQUENCY ATLAS OF THE MIDWEST

Bulletin 71

(MCC Research Report 92-03)

RAINFALL FREQUENCY ATLAS OF THE MIDWEST

by Floyd A. Huff and James R. Angel

Midwestern Climate Center

Climate Analysis Center

National Weather Service

National Oceanic and Atmospheric Administration

and

Illinois State Water Survey

A Division of the Illinois Department of Energy and Natural Resources

1992

Bulletin 71

(MCC Research Report 92-03)

RAINFALL FREQUENCY ATLAS OF THE MIDWEST

by Floyd A. Huff and James R. Angel

Title: Rainfall Frequency Atlas of the Midwest.

Abstract: This report presents the results and methodology of an intense study of rainfall

frequency relationships throughout the Midwest (Illinois, Indiana, Iowa, Kentucky,

Michigan, Minnesota, Missouri, Ohio, and Wisconsin). Using primarily 275 long-term

daily reporting stations from the National Weather Service (NWS) cooperative network

supplemented by 134 daily reporting stations with shatter records, rainfall amounts have

been determined for recurrence intervals from 2 months to 100 years and for durations of

5 minutes to 10 days. The results are presented as maps and as climate division averages

in tabular form. Several special raingage networks were used to develop relationships

between amounts for 24 hours and less. This report also examines the time distributions of

heavy rainfall over time, and other storm characteristics such as storm orientation and

movement. The assumption of spatially independent observations between stations is also

discussed.

Reference: Huff, Floyd A., and James R. Angel. Rainfall Frequency Atlas of the Midwest.

Illinois State Water Survey, Champaign, Bulletin 71, 1992.

Indexing Terms: Climatology, heavy rainfall, hydroclimatology, hydrometeorology,

Midwest, extreme value distributions, climate change.

The Midwestern Climate Center (MCC) is funded by a grant from the Climate Analysis Center,

National Weather Service, National Oceanic and Atmospheric Administration,

U.S. Department of Commerce

STATE OF ILLINOIS

HON. JIM EDGAR, Governor

DEPARTMENT OF ENERGY AND NATURAL RESOURCES

John S. Moore, B.S., Director

BOARD OF NATURAL RESOURCES AND CONSERVATlON

John S. Moore, B.S., Chair

Robert H. Benton, B.S.C.E., Engineering

Donna M. Jurdy, Ph.D., Geology

H.S. Gutowsky, Ph.D., Chemistry

Roy L. Taylor, Ph.D., Plant Biology

Robert L. Metcalf, Ph.D., Biology

W.R. ¡°Reg¡± Gomes, Ph.D.

University of Illinois

John H. Yopp, Ph.D.

Southern Illinois University

STATE WATER SURVEY DIVISION

JOHN T. O¡¯CONNOR, Chief

2204 GRIFFITH DRIVE

CHAMPAIGN, ILLINOIS 61820-7495

1992

ISSN 0360-9804

Funds derived from grants and contracts administered by

the University of Illinois were used to produce this report.

This report was printed on recycled and recyclable paper.

Printed by authority of the State of Illinois (12-92-1.6M)

CONTENTS

Page

Introduction ..................................................................................................................................

Storms in the Midwest ........................................................................................................

Rationale for the Study .......................................................................................................

Organization of the Report ..................................................................................................

Basic Considerations...........................................................................................................

Pilot Study .........................................................................................................................

Information Accumulated for Each State.................................................................

Acknowledgments .............................................................................................................

1

1

1

2

2

3

3

3

Part 1. Analyses .............................................................................................................................

1. Data and Analytical Approach ....................................................................................................

5

5

2. Statistical Methods..................................................................................................................... 7

Background........................................................................................................................ 7

Analytical Method Employed in the Nine-State Study........................................................... 7

Comparison of Huff-Angel, L-moments, and Maximum Likelihood Methods'

Fitting Procedures for Selected States .................................................................................. 8

Maximum Likelihood Method ................................................................................. 8

L-moments Method................................................................................................. 8

L-moments Regions ................................................................................................ 8

Results ................................................................................................................... 9

Indiana ....................................................................................................... 9

Minnesota................................................................................................... 10

3. Frequency Distributions of Heavy Rainfall Events ....................................................................... 18

Point Rainfall Frequency Distributions................................................................................. 18

Areal Mean Frequency Distributions.................................................................................... 18

4. Time Distributions of Rainfall in Heavy Storms...........................................................................

Method and Results of Analysis...........................................................................................

Application of Results.........................................................................................................

Using Results in Structural Design Problems: Case Studies ...................................................

Case One................................................................................................................

Case Two ...............................................................................................................

Case Three .............................................................................................................

20

20

20

20

20

20

20

5. Seasonal Distributions of Heavy Rainfall.....................................................................................

Background........................................................................................................................

Analysis and Results...........................................................................................................

Seasonal Precipitation .............................................................................................

Seasonal Distribution of Heavy Rainstorms .............................................................

Rainfall Frequencies by Season................................................................................

Summary ...........................................................................................................................

25

25

25

25

25

25

28

CONTENTS (Concluded)

6. Fluctuations in Frequency Distributions of Heavy Rainstorms in the Midwest ................................

Background .............................................................................................................................

Analytical Approach and Results ............................................................................................

Illinois ........................................................................................................................

The Midwest ..............................................................................................................

Summary and Conclusions .....................................................................................................

32

32

32

32

33

34

7. Spatial Characteristics of Heavy Rainstorms in the Midwest ...........................................................

Relation Between Point and Areal Mean Rainfall Frequency ..................................................

Storm Shape ...........................................................................................................................

Storm Orientation....................................................................................................................

Storm Movement ....................................................................................................................

36

36

36

37

37

8. Independence of Extreme Rainfall Events .......................................................................................

Examples of Outstanding Storms ............................................................................................

Additional Analyses ...............................................................................................................

Summary ................................................................................................................................

38

38

41

44

9. Variability within Climatic Sections................................................................................................ 45

10. General Summary and Conclusions...............................................................................................

Data and Analytical Approach ................................................................................................

Statistical Methods .................................................................................................................

Frequency Distributions of Heavy Rainfall Events ..................................................................

Point Rainfall Frequency Distributions .......................................................................

Areal Mean Rainfall Frequency Distributions .............................................................

Time Distributions of Rainfall in Heavy Storms ......................................................................

Seasonal Distribution of Heavy Rainfall .................................................................................

Temporal Fluctuations in Frequency Distribution of Heavy Rainstorms ...................................

Other Studies...........................................................................................................................

48

48

48

48

48

48

49

49

49

49

References........................................................................................................................................... 50

Part 2. Spatial Distribution Maps and Sectional Mean Frequency Distribution Tables .......................... 53

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